000
AXPZ20 KNHC 120231
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC FRI JUL 12 2013

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...   
     
THE MONSOON TROUGH AXIS EXTENDS W FROM THE NW COAST OF COLOMBIA 
AT 10N76W ACROSS THE CARIBBEAN ALONG 11N TO ACROSS NORTHERN 
COSTA RICA TO THE COAST OF COSTA RICA AT 11N85W...CONTINUING W 
TO 11N106W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN 
INTERTROPICAL CONVERGENCE ZONE. THIS ITCZ THEN CONTINUES NW TO 
12N121W...THEN TURNS ABRUPTLY SW TO 07N130W...THEN WESTWARD TO 
BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
OBSERVED S OF THE MONSOON TROUGH WITHIN 150 NM EITHER SIDE OF A 
LINE FROM 06N83W TO 10N105W...S OF THE ITCZ WITHIN 15 NM EITHER 
SIDE OF A LINE FROM 08N106W TO 10N109W TO 08N117W. ISOLATED 
MODERATE TO OCCASIONALLY STRONG CONVECTION IS NOTED ELSEWHERE N 
OF 10N E OF 96W AND N OF THE ITCZ WITHIN 150 NM EITHER SIDE OF A 
LINE FROM 13N111W TO 12N140W...AND ALONG THE ITCZ WITHIN 30 NM 
OF 06.5N131W.

...DISCUSSION... 

A NEGATIVE TILT UPPER TROUGH EXTENDS INTO THE NW PORTION OF THE 
DISCUSSION AREA ALONG 32N132W TO 26N130W. AN UPPER ANTICYCLONE W 
OF THE AREA NEAR 22N147W HAS A RIDGE EXTENDING E TO A CREST 
WITHIN THE DISCUSSION AREA AT 22N130W. THESE UPPER LEVEL SYSTEMS 
COMBINE TO DRY OUT THE UPPER LEVELS OF THE DISCUSSION AREA TO 
THE N OF 18N AND TO THE W OF 117W.

A BROAD INVERTED UPPER TROUGH...ACCOMPANIED BY DRY AIR ALOFT... 
DOMINATES THE DEEP TROPICS S OF 07N BETWEEN 113W-136W WITH THE 
PATTERN SHIFTING W WITH TIME. THE UPPER FLOW IS SLIGHTLY 
DIFFLUENT S OF THE PREVIOUSLY MENTIONED SUBTROPICAL UPPER RIDGE 
AND TO THE N OF THIS BROAD TROUGH...AND IS ENHANCING THE 
ISOLATED CONVECTION PREVIOUSLY DESCRIBED BETWEEN 113W-140W. THE 
RESULTANT DEBRIS MOISTURE APPEARS VERY THIN...AND IS ADVECTED W 
ACROSS THE TROPICS FROM 10N-15N BETWEEN 115W-140W.

A SMALL UPPER ANTICYCLONE IS CENTERED NEAR 22N117W WITH AN UPPER 
RIDGE EXTENDING S TO A BASE AT 17N105W WITH UPPER MOISTURE 
TRAPPED WITHIN THE RIDGE.  

AN UPPER CYCLONE IS STATIONARY OVER CENTRAL OLD MEXICO AT 22N99W 
WITH AN UPPER TROUGH EXTENDING SW TO A BASE NEAR 15N102W. AN 
UPPER ANTICYCLONE IS OVER NICARAGUA WITH ITS ENVELOPE OF 
ANTICYCLONIC FLOW DOMINATING THE TROPICAL PACIFIC E OF THE JUST 
DESCRIBED UPPER TROUGH. THE ASSOCIATED DIFFLUENCE IS ENHANCING 
THE CONVECTION ACROSS THE WATERS E OF 108W. THE RESULTANT DEBRIS 
MOISTURE FROM THIS CONVECTION HAS MOISTENED THE UPPER LEVELS N 
OF 02N BETWEEN 73W-103W. 

AT THE LOW LEVELS A RIDGE EXTENDS FROM 30N140W TO 15N108W WITH 
NE TRADES AT 15-20 KT ACROSS THE TROPICS FROM 13N-20N W OF 120W 
WITH SEAS OF 5-7 FT IN MIXING NE AND S SWELL.  

SOUTHERLY CROSS EQUATORIAL SWELL IS MAINTAINING COMBINED SEAS OF 
6-8 FT ACROSS THE TROPICAL WATERS S OF 08N BETWEEN 105W-118W. 
THESE SWELLS ARE FORECAST TO CONTINUE TO SUBSIDE WITH COMBINED 
SEAS BELOW 8 FT BY FRI AFTERNOON.
 
$$ 
NELSON